[quality] scripts/html-pages.mjs page-discovery helper has no direct unit test — gates can pass vacuously #178

Finding

scripts/html-pages.mjs exports htmlFiles(), isRedirectPage(), lineOf() and SKIP_DIRS. Ten static gates (page-meta, page-csp, page-images, page-markup, page-structure, page-404, page-scripts, jsonld-contract, redirect-targets, ci-wiring) import it to decide which pages they inspect — but no test exercises the helper itself.

The failure mode is silent: if SKIP_DIRS gained a content directory (e.g. stories), or the walker stopped recursing, or isRedirectPage() stopped matching the generator's <meta http-equiv="refresh">, no gate would fail — each would simply run over fewer pages and pass vacuously. Mutation check at 6e7faba: each of those three edits leaves node --test scripts/*.test.mjs fully green today.

This is the same class of gap #177 closed for scripts/actions-if.mjs.

Evidence: unit — node --test scripts/*.test.mjs @ 6e7faba: 537 pass, 0 direct tests for html-pages.mjs (grep -l 'html-pages.mjs' scripts/*.test.mjs → importers only). End-to-end — the links.yml test job runs the same glob, so it inherits the same blind spot; no separate e2e coverage source exists for this repo.

Recommendation

Add scripts/html-pages.test.mjs (direct unit test, zero dependencies, fits the existing node --test scripts/*.test.mjs glob so no workflow edit is needed):

• htmlFiles() on a temp tree: recursion, sorted output, .html-only (not .htm/.HTML/.html.bak), skips exactly SKIP_DIRS at any depth and only as directories, [] on empty tree
• SKIP_DIRS equals the known tooling set and never names a content directory
• isRedirectPage() positive variants (quote style, case, whitespace around =, attribute order, multi-line) and negatives (CSP / content-type http-equiv, name="refresh", prose)
• lineOf() 1-based semantics
• live-tree pins: index.html, 404.html, stories/index.html and every make-redirects.sh MAP page are discovered; nothing under a skipped dir is; redirect pages == MAP paths
• README ## Checks entry (required by ci-wiring.test.mjs)

Priority

• Impact: medium (guards the non-vacuity of every other page gate)
• Effort: low

Filed by quality agent (ACMM L4/L6 — full mode)

🐝 Hive Agent: quality | Instance: hosted-available-oke-11-placeholder-r05x | SHA: 6e7faba

— hive: agent=quality backend=copilot model=claude-fable-5.1 copilot=1.0.88